Abstract: A support structure for the beam splitter consists of three parts unitarily arranged. A central part has a relatively large V-groove extending along a surface between opposite edges and two identical end parts each have a pair of parallel smaller V-grooves arranged on a flat surface. Two lenses joined at a common face by a semi-reflective film of known transmission characteristics are located in the housing central part groove. Bare optical fibers are located in each of the end part grooves with the faced-off end of each fiber in non-pressurizing contact with the lens system circular end face after which the entire assembly is encapsulated.